Low-Stress Training vs. High-Stress Plant Training Techniques 

Low-Stress Training (LST) and High-Stress Training (HST) are two popular methods for optimizing plant growth and maximizing yield. LST involves gentle, gradual techniques to shape plants without stress, promoting healthy development. In contrast, high-stress training uses more aggressive methods to encourage desirable traits, such as multiple colas or increased flowering, which are essential for growers aiming to enhance productivity and plant health.

The Science Behind Low-Stress Training

To effectively implement LST, it really helps to have an understanding of how cannabis responds to bending and positional changes, especially regarding cellular and hormonal mechanisms. Cannabis plants exhibit cell elongation and redistribution of hormones, notably auxin, which impacts growth patterns. Additionally, it shows strong apical dominance, where the main shoot’s high auxin levels suppress lateral bud growth, promoting increased vertical growth. 

When the main shoot is bent, it alters gravity perception through statolith redistribution, leading to auxin migration from the apex to lower regions, which reduces its concentration at the tip. This decrease allows cytokinin to activate lateral buds, resulting in uniform growth of multiple colas with similar hormonal profiles. Additionally, hormonal changes induce long-term epigenetic modifications that support horizontal growth and development.

When to Begin Low-Stress Training

Photoperiodic strains should be chosen between the fourth and sixth nodes, when stems are flexible but sturdy enough for gentle bending. Indicators include a stem diameter of about four millimeters, the ability to bend 90° without cracking, and roots visible at the bottom of the pot. Healthy plant growth features internodes spaced 2 to 4 centimeters apart, 5 to 7-fingered fan leaves, and a growth rate of 1 to 2 centimeters per day. 

Regarding cannabis autoflowers, it is highly beneficial to initiate Low Stress Training (LST) at an early stage of plant development. The optimal time to start this training technique is when the plant has about three to four nodes, typically between 16 and 20 days old. During this period, lateral shoots should reach about three to five centimeters in length. Early intervention can maximize yield and accommodate the plant’s accelerated metabolism.

A Step-by-Step Guide to Low-Stress Training

Low-stress Sea of Green (SOG) training technique.

Low-Stress Training is suitable for a range of experience levels and growing environments. It begins with careful preparation, including a thorough assessment of the plant, including leaf color, stem flexibility, root health, nutrient schedule, and environmental stability. 

1. To perform this technique on your plants, start by gently manipulating the stem between your fingers, then bend it and secure it with soft ties to stakes or the pot’s edge without causing damage.
2. After the initial bend, focus shifts to managing lateral branches. As these shoots grow, they are arranged to form an even canopy, which helps improve light distribution and airflow. This involves selecting the most vigorous shoots as future colas, evenly spacing the branches, and making regular adjustments every few days to promote optimal growth. This stage highlights maintaining symmetry and removing any pockets of stagnant air from the canopy.
3. Finally, during the last vegetative weeks, focus on perfecting the canopy layout and preparing for flowering. Fine adjustments can be made daily to ensure uniform height and healthy development. 
4. As the plant transitions into flowering, the approach becomes more stable, with less emphasis on bending and more on reinforcing structures. Strategically removing leaves can improve light penetration, maximize plant health, and optimize yield.

The Science Behind High-Stress Training

High-stress training (HST) involves intentionally damaging plants to stimulate new growth. The injury triggers biological responses, with cells near the wound releasing signals like calcium and reactive oxygen species to aid repair. For example, decreasing auxin levels encourages bushier plants; cytokinins stimulate new shoot development; jasmonic acid boosts terpene and cannabinoid production, along with ethylene, which strengthens stems.

When cells are damaged, the formation of callus tissue begins, which is further enhanced by the addition of lignin, a complex organic polymer, resulting in the development of the characteristic knuckles on super-cropped branches. Such stress responses also stimulate increased resin production, which can benefit the plant’s defense mechanisms. However, excessive stress may hinder growth or potentially cause hermaphroditism.

Five High-Stress Training Techniques

So, let’s dive into the top five most popular high-stress techniques and see which one truly resonates with your garden passions.

Super-cropping

Super-cropping is a horticultural technique that involves carefully pinching and bending cannabis plant stems at the nodes. This controlled injury stimulates the plant to develop additional strength and fibrous tissue, resulting in a more robust structure. By improving airflow and light penetration within the plant canopy, super-cropping enhances overall plant health, promotes better nutrient distribution, and can significantly increase crop yields.

FIMMING

FIMMING, also known as “Fuck I Missed,” is used to promote bushier growth and higher yields. It involves pinching or cutting off the new growth tip from the apical meristem, typically around three weeks into the plant’s vegetative stage. This encourages the plant to develop additional branches and nodes, resulting in a fuller canopy. FIMMING improves light penetration and airflow, which ultimately leads to more bud sites and increased production.

Topping

Topping encourages plants to develop more branches, resulting in a bushier plant and potentially higher yields. It involves cutting off the main stem just above a node, which stimulates the plant to grow two new branches from that point. This method enhances light exposure and airflow, both of which promote healthy growth. Topping is popular among growers aiming to maximize production, improve plant shape, and maintain better control.

Mainlining

Mainlining is a highly stressful training technique used to encourage the growth of larger, more uniform cannabis buds by topping the plant multiple times to produce several main apical stems. The process involves removing growth below the main sites, tying down branches to promote even light distribution, and pruning to create a symmetrical shape. This results in bigger, well-spaced buds and simplifies the harvesting and trimming process.

Defoliation

Defoliation practices vary among cultivators and involve systematically removing leaves throughout the plant’s growth cycle. During the vegetative stage, large fan leaves are removed to enhance light penetration. Additional leaf removal is typically performed before the onset of flowering and throughout the following weeks. This stress stimulates increased calyx production during the stretch period, thereby increasing yield potential.

When to Begin High-Stress Training

High-stress training can be applied to plants once they have established a strong, healthy structure. Typically, growers begin implementing methods such as topping or pruning during the vegetative stage, which usually occurs when the plants are around three to four weeks old. It’s important to ensure the plants are relatively robust at this point, as they need the strength to withstand the stress of these techniques without compromising their health.

It is generally not advisable to use high-stress training methods on autoflowering plants, especially given their inherently short, fixed growth cycle. Techniques such as pruning, super cropping, or defoliation can induce significant stress, potentially stunting growth and reducing yield. Since autoflowers have limited vegetative time, they require gentle handling and minimal interference to ensure optimal development and an XL harvest.

A Step-by-Step Guide to High-Stress Training

High-Stress Training (HST) is designed for experienced growers who want to enhance their yield and refine plant shape. Similar to Low-Stress Training (LST), it begins with a thorough plant inspection—checking stem strength and overall health to ensure the plant is ready. Once prepared, techniques such as topping and super cropping can be used to promote the growth of multiple colas, strengthen the plant’s structure, and improve light penetration.

1. Following the initial injury or manipulation, manage the plant’s response by selectively pruning or training the lateral branches. Carefully remove shoots to redirect growth, aiming to develop an even canopy or shape the plant for optimal light exposure. 
2. Regularly assess the plant’s recovery and make adjustments as needed to maintain balance and encourage vigorous branching. This stage requires patience and attention to promote healthy regrowth.
3. As the plant approaches the flowering stage, refine the canopy structure by removing ineffective growth and strengthening the main stems. These final adjustments help maximize light penetration and airflow. During this period, focus on maintaining the plant’s stability and vigor, reinforcing the structure if needed, and avoiding unnecessary stress that could hinder flowering, leading to significantly increased yields and a more manageable plant shape.

Choosing the Right Training Technique for You

Low-Stress Training is a great starting point for beginners, providing an easy way to learn about plant biology and boost yields. As your confidence builds, exploring High-Stress Methods like pruning can maximize yields, though they demand more skill. By experimenting responsibly with both techniques, you’ll discover what works best for your plants and abilities. Practice can help refine your skills and enjoy healthier, more productive harvests.